Most zoning codes and development practices require generous parking supply, forcing people who purchase or rent housing to pay for parking regardless of their demands. Generous parking requirements reduce housing affordability and impose various economic and environmental costs. Based on typical affordable housing development costs, one parking space per unit increases costs approximately 12.5%, and two parking spaces can increase costs by up to 25%. Since parking costs increase as a percentage of rent for lower priced housing, and low income households tend to own fewer vehicles, minimum parking requirements are regressive and unfair. Various parking management strategies can increase affordability, economic efficiency and equity.

This report indicates that generous, inflexible parking requirements are inefficient and inequitable, since they fail to provide an expensive resource (parking) in proportion to need (vehicle ownership). Parking demand varies between households, between neighborhoods, and over time for individual households. Smaller, lower income households located in accessible areas tend to own fewer cars. A typical house or apartment unit may at various times house residents with zero, one, two or three vehicles.

Parking is a costly resource. Parking typically represents 10-20% of the cost of housing. This cost may be acceptable to most middle and upper income households, which tend to own multiple vehicles and can afford the extra expense, but for lower income families generous parking requirements impose significant financial burdens.

Excessive parking requirements impose several costs on society. They increase development costs of lower-priced housing, reducing housing affordability. Minimum parking requirements are regressive because they force residents to pay for parking facilities, even if they do not own a vehicle. They increase vehicle ownership, and therefore problems such as traffic congestion, accidents and pollution emissions. Generous parking requirements discourage infill development and increase sprawl, increasing impervious surface coverage and per capita vehicle travel. They shift lower-income households to suburban and exurban areas where land prices are low but transport and public service costs are high.

For typical affordable housing in urban locations, where parking represents 20% of residential build costs and parking demand is less than 50% of conventional parking standards, applying more accurate and flexible parking requirements can reduce housing costs by 10%, and even more if additional parking management strategies are implemented. For households that do not own an automobile, more accurate parking requirements and unbundling parking costs can reduce rents by 10-20%.

Most households, including those with low incomes, own at least one vehicle and therefore need residential parking. Even non-drivers want parking for visitors. It is therefore important that parking policy reforms be realistic and avoid creating new problems. Better parking management practices have proven successful at reducing residential parking costs, increasing housing affordability and supporting other strategic land use objectives, such as supporting infill development, improving community accessibility and reducing sprawl. This involves creating more accurate and flexible parking standards, unbundling parking from building space so residents pay for parking facilities based on the number of spaces they actually use, and appropriate enforcement to minimize spillover problems.

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